A white LED is one of next-generation light-emitting elements which can replace the existing general lights, and the white light-emitting diode has been manufactured by mixing three-primary-colored light-emitting diodes since red, green and blue light-emitting diodes having a high luminance began to be commercialized.
Due to a remarkable development of technology, a yellow fluorescent substance can be excited by a blue light source having a wavelength of 460 nm using a blue light-emitting diode having sufficient excited energy, and thus a white light-emitting diode can be manufactured by mixing blue and yellow.